1. Field of the Invention
The present invention provides a ladder for horizontal blinds. More particularly, preferred embodiments of the ladder provide a drawstring that is pre-threaded through external loops on the ladder.
2. Description of the Related Art
Horizontal blinds typically comprise rows of horizontal slats that hang in front of a window. An exemplary set of horizontal blinds 10 is depicted in FIG. 2. The slats 12 are typically supported from a headrail 14 by ladders 16. A set of blinds generally includes at least two spaced ladders, and often up to four or five spaced ladders, depending upon the length of the slats. The ladders 16 are connected to a tilting mechanism within the headrail 14, which is often manipulable through a rotatable vertical rod 18 or a loop chain. Adjusting the angle of tilt of the slats regulates the amount of exterior light that penetrates to the interior of the building through the window. An interior of the headrail may contain tape drums, rollers, lift cord actuators and locks, tilting mechanisms, tilt rods, etc. for tilting and raising/lowering the slats.
The ladders 16 (shown in detail in FIG. 3) typically include a pair of vertical legs 20 supporting a plurality of spaced horizontal rungs 22. Each rung may comprise a pair of cords so that the slats may be inserted between the cords, facilitating rotation of the slats. Each leg 20 is connected at a bottom end to a bottom rail, which is typically thicker and heavier than the slats. From the bottom rail, each leg runs vertically upward to the headrail 14. The upper extent of each leg is usually connected to a tilting mechanism in the headrail. The tilting mechanism shortens one leg while releasing some slack in the other leg to rotate the slats about a longitudinal axis of each slat. The orientation of each slat about its longitudinal axis controls the amount of light that penetrates the blinds.
Most ladders include one or more pull cords 24 (FIG. 3). Each pull cord 24 is secured at a bottom end to the bottom rail, and rises vertically to the headrail 14. An upper end of each pull cord 24 passes into the headrail, around a pulley, horizontally toward one end of the headrail, around a second pulley, and out through an opening in the bottom of the headrail (FIG. 2). A free end of each pull cord is usually joined together with the free ends of the other pull cords in a knot. This knot is typically enclosed by a decorative cover 26. Pulling downward on the free ends of the pull cords raises the bottom rail by drawing the pull cords around the pulleys in the headrail. As the bottom rail rises, it contacts the lowermost slat, which in turn contacts the next lowermost slat, etc. The pull cords and the bottom rail thus control the raising and lowering of the blinds.
In one common configuration, the pull cord comprises a third leg positioned between the two outside legs. This third leg usually passes through a hole in each slat. In this configuration, the outside legs serve merely to retain the slats, preventing them from exiting the ladders in a lateral direction. The central leg both prevents the slats from sliding out of the ladders in a lengthwise direction, and raises and lowers the blinds.
In another common configuration, shown in FIGS. 2 and 3, one or both legs includes a plurality of evenly spaced loops 28 (FIG. 3) on an outward facing side. One or two pull cords 24 (depending upon whether one or both legs includes loops) pass through the loops 28. In this configuration, the legs again prevent the slats from exiting the ladders in a lateral direction. Typically the slats include notches 30 along their edges corresponding to the positions of the legs 20. The mating fit between the legs 20 and notches 30 prevents the slats from sliding lengthwise out of the ladders 16. The pull cords facilitate raising and lowering of the blinds.
Typically, horizontal blinds are assembled in one location using various components, for example, slats, ladders and headrails, that are each manufactured in separate locations. When assembling horizontal blinds using ladders having loops, the pull cord(s) must be threaded through the loops during assembly. In prior art assemblies, this threading has been a very labor-intensive process, requiring a factory worker to thread the pull cord through each loop by hand. This process is tedious and takes a great deal of time. Because of the time required, the labor costs associated with producing these blinds are high. The high labor costs result in a more expensive end product.
Thus, a ladder for horizontal blinds that simplifies the assembly process would reduce the retail price of horizontal blinds, making them more affordable for consumers.